This invention relates to the field of guidewires for advancing intraluminal devices such as stent delivery catheters, balloon dilatation catheters, atherectomy catheters and the like within body lumens.
In a typical percutaneous coronary procedure, a guiding catheter having a pre-formed distal tip is percutaneously introduced into a patient""s peripheral artery, e.g. femoral or brachial artery, by means of a conventional Seldinger technique and advanced therein until the distal tip of the guiding catheter is seated in the ostium of a desired coronary artery. A guidewire is first advanced by itself through the guiding catheter until the distal tip of the guidewire extends beyond the arterial location where the procedure is to be performed. Then a rapid exchange type catheter, such as described in U.S. Pat. No. 5,061,273 (Yock) is mounted onto the proximal portion of the guidewire which extends out of the proximal end of the guiding catheter which is outside of the patient. The catheter is advanced over the guidewire, while the position of the guidewire is fixed, until the operative element on the rapid exchange type catheter is disposed within the arterial location where the procedure is to be performed. After the procedure is performed, the rapid exchange type catheter may be withdrawn from the patient over the guidewire or the guidewire repositioned within the coronary anatomy for an additional procedure.
A guidewire may also be used in conjunction with the delivery of an intracoronary stent. One method and system involves disposing a compressed or otherwise small diameter stent about an expandable member such as a balloon on the distal end of a catheter, advancing the catheter through the patient""s vascular system over a guidewire until the stent is in the desired location within a blood vessel. The expandable member on the catheter may then be expanded to expand the stent within the blood vessel. The dilated expandable member is then contracted and the catheter withdrawn, leaving the expanded stent within the blood vessel, holding the passageway thereof open. This latter method and system can be used concurrently with balloon angioplasty or subsequent thereto.
Further details of guidewires, and devices associated therewith for various interventional procedures can be found in U.S. Pat. No. 4,748,986 (Morrison et al.); U.S. Pat. No. 4,538,622 (Samson et al.); U.S. Pat. No. 5,135,503 (Abrams); U.S. Pat. No. 5,341,818 (Abrams et al.); and U.S. Pat. No. 5,345,945 (Hodgson, et al.) which are hereby incorporated herein in their entirety by reference thereto.
Conventional guidewires for angioplasty, stent delivery, atherectomy and other intravascular procedures usually have an elongate core member with one or more segments near the distal end thereof which taper distally to smaller cross sections. A flexible body member, such as a helical coil or a tubular body of polymeric material, is typically disposed about and secured to at least part of the distal portion of the core member. A flexible core segment, which may be the distal extremity of the core member or a separate shapeable ribbon which is secured to the distal extremity of the core member extends through the flexible body and is secured to the distal end of the flexible body by soldering, brazing or welding, or an adhesive in the case of polymeric flexible bodies which forms a rounded distal tip. The leading tip is highly flexible and will not damage or perforate the vessel and the portion behind the distal tip is increasingly stiff which better supports a balloon catheter or similar device.
The flexible core segment or ribbon of a typical guidewire is a small diameter wire which has been flattened to a relatively constant transverse profile. Flattening of the flexible core segment facilitates the shapability of the member. However, a flexible core segment having a constant transverse profile or flexibility can be subject to prolapse during use. Prolapse occurs when the flexible core segment gets bent back on itself in a constrained lumen and is difficult to straighten out with proximal manipulation. The present invention satisfies these and other needs.
The present invention is directed to a guidewire having an elongate core member with a proximal core section and a distal core section, and a flexible body disposed about and secured to at least a portion of the distal core section. The guidewire has an elongated, preferably shapeable flexible core segment which is secured to or which is formed as part of the distal core section and which is secured to the distal end of the flexible body disposed about the distal core section. The distal core section may have one or more tapered sections proximal to the flexible core segment which have distally decreasing tapers with substantially round transverse cross sections.
The tapered, preferably shapeable flexible core segment has a double reverse taper, i.e. a first transverse dimension which distally tapers over a substantial length thereof from a first value to a second smaller value and a second transverse dimension which distally tapers over essentially the same length of the flexible core segment from a first value to a second larger value, i.e. flares outwardly. The length of the tapered flexible core segment is about 1 to about 12 cm, preferably about 2 to about 10 cm. At least 50%, preferably at least 75% of the length of the tapered flexible core segment is tapered as described above. The distal most portion of the flexible core segment (i.e. up to about 15 mm) may be flat with one or both of the opposed faces being parallel. The tapers may be straight or curved.
The flexible core segment preferably has two pairs of opposing faces which are essentially the mirror image of each other. In one of the pairs the opposing faces converge toward each other while in the other pair the opposing faces diverge from each other.
The flexible core segment may be formed integrally or out of the distal extremity of the distal core section or may be formed as a distinct structural component or shaping ribbon which needs to be mounted in a suitable manner to the distal core section, e.g. by welding, brazing, soldering, adhesive bonding, mechanical connections and other known mounting processes. The flexible core segment may by formed from round or flattened wire and may be coined or rolled or otherwise plastically deformed, e.g. cold forged, to a desired shape and sectional profile. When the flexible core segment is a separate member from the core member, it may be formed before or after it is secured to the core member.
The flexible body member is disposed about the flexible core segment, preferably along its entire length and may take the form of a helical coil, polymer jacket, or the like. The distal end of the flexible body member is secured to the distal end of the flexible core segment and an intermediate portion of the flexible body member is preferably secured to the distal core section proximal to the tapered flexible core segment.
The double taper of the flexible core segments on the distal part of the guidewire reduces the likelihood of prolapsing or kinking of the guidewire""s distal extremity during procedures and may be used to provide a controlled longitudinal variation and transition in flexibility of the core segment to the distal tip of the guidewire. A flexible body member, such as a helical coil or a tubular plastic member, having a proximal end and a distal end is typically disposed about and secured to the distal section of the elongate core member.
The taper geometry of the flexible segment may be modeled mathematically. Specific taper or face contours may be selected in keeping with the principles of the invention to achieve optimum performance for specific usage requirements. These and other advantages of the invention will become more apparent from the following detailed description of the invention when taken in conjunction with the accompanying exemplary drawings.